66 lines
1.8 KiB
C
66 lines
1.8 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Check user and group names for illegal characters
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*
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* Copyright (C) 2008 Tito Ragusa <farmatito@tiscali.it>
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*
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* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
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#include "libbb.h"
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#ifndef LOGIN_NAME_MAX
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#define LOGIN_NAME_MAX 256
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#endif
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/* To avoid problems, the username should consist only of
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* letters, digits, underscores, periods, at signs and dashes,
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* and not start with a dash (as defined by IEEE Std 1003.1-2001).
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* For compatibility with Samba machine accounts $ is also supported
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* at the end of the username.
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*/
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void FAST_FUNC die_if_bad_username(const char *name)
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{
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const char *start = name;
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/* 1st char being dash or dot isn't valid:
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* for example, name like ".." can make adduser
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* chown "/home/.." recursively - NOT GOOD.
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* Name of just a single "$" is also rejected.
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*/
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goto skip;
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do {
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unsigned char ch;
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/* These chars are valid unless they are at the 1st pos: */
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if (*name == '-'
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|| *name == '.'
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/* $ is allowed if it's the last char: */
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|| (*name == '$' && !name[1])
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) {
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continue;
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}
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skip:
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ch = *name;
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if (ch == '_'
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/* || ch == '@' -- we disallow this too. Think about "user@host" */
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/* open-coded isalnum: */
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|| (ch >= '0' && ch <= '9')
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|| ((ch|0x20) >= 'a' && (ch|0x20) <= 'z')
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) {
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continue;
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}
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bb_error_msg_and_die("illegal character with code %u at position %u",
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(unsigned)ch, (unsigned)(name - start));
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} while (*++name);
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/* The minimum size of the login name is one char or two if
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* last char is the '$'. Violations of this are caught above.
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* The maximum size of the login name is LOGIN_NAME_MAX
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* including the terminating null byte.
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*/
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if (name - start >= LOGIN_NAME_MAX)
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bb_simple_error_msg_and_die("name is too long");
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}
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